package com.zhang.superAiHospital.utils;
import java.security.MessageDigest;

public class MD5Util {

	 /**
     * 单例
     */
    private static MD5Util instance;

    /**
     * 四个链接变量
     */
    private final int A = 0x67452301;
    private final int B = 0xefcdab89;
    private final int C = 0x98badcfe;
    private final int D = 0x10325476;

    /**
     * ABCD的临时变量
     */
    private int Atemp;
    private int Btemp;
    private int Ctemp;
    private int Dtemp;

    /**
     * 常量ti
     * 公式:floor(abs(sin(i+1))×(2pow32)
     */
    private final int[] K = {
                0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
                0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501, 0x698098d8,
                0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193,
                0xa679438e, 0x49b40821, 0xf61e2562, 0xc040b340, 0x265e5a51,
                0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
                0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905,
                0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a, 0xfffa3942, 0x8771f681,
                0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60,
                0xbebfbc70, 0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
                0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665, 0xf4292244,
                0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92,
                0xffeff47d, 0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314,
                0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
    };

    /**
     * 向左位移数,计算方法未知
     */
    private final int[] s = {
            7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7,
            12, 17, 22, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
            4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 6, 10,
            15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21
    };

    /**
     * 私有构造函数
     */
    private MD5Util() {

    }

    /**
     * 单例模式
     * @return
     */
    public static MD5Util getInstance() {
        if (instance == null) {
            instance = new MD5Util();
        }
        return instance;
    }

    /**
     * 初始化函数
     */
    private void init() {
        Atemp = A;
        Btemp = B;
        Ctemp = C;
        Dtemp = D;
    }

    /**
     * 移动一定位数
     * @param a
     * @param s
     * @return
     */
    private int shift(int a, int s) {
        return (a << s) | (a >>> (32 - s)); // 右移的时候，高位一定要补零，而不是补充符号位
    }

    /**
     * 主循环
     * @param M
     */
    private void mainLoop(int[] M) {
        int F;
        int g;
        int a = Atemp;
        int b = Btemp;
        int c = Ctemp;
        int d = Dtemp;

        for (int i = 0; i < 64; i++) {
            if (i < 16) {
                F = (b & c) | ((~b) & d);
                g = i;
            }else if (i < 32) {
                F = (d & b) | ((~d) & c);
                g = (5 * i + 1) % 16;
            }else if (i < 48) {
                F = b ^ c ^ d;
                g = (3 * i + 5) % 16;
            } else {
                F = c ^ (b | (~d));
                g = (7 * i) % 16;
            }

            int tmp = d;
            d = c;
            c = b;
            b = b + shift(a + F + K[i] + M[g], s[i]);
            a = tmp;
        }

        Atemp += a;
        Btemp += b;
        Ctemp += c;
        Dtemp += d;
    }

    /**
     * 填充函数
     * 处理后应满足bits≡448(mod512),字节就是bytes≡56（mode64)
     * 填充方式为先加一个0,其它位补零
     * 最后加上64位的原来长度
     * @param str
     * @return
     */
    private int[] add(String str) {
        int num = ((str.length() + 8) / 64) + 1;    // 以512位，64个字节为一组
        int[] strByte = new int[num * 16];  // 64/4=16，所以有16个整数

        for (int i = 0; i < num * 16; i++) {
            // 全部初始化为0
            strByte[i] = 0;
        }

        int j;
        for (j = 0; j < str.length(); j++) {
            strByte[j >> 2] |= str.charAt(j) << ((j % 4) * 8);  // 一个整数存储四个字节，小端序
        }
        strByte[j >> 2] |= 0x80 << ((j % 4) * 8);   // 尾部添加1

        // 添加原长度，长度指位的长度，所以要乘8，然后是小端序，所以放在倒数第二个,这里长度只用了32位
        strByte[num * 16 - 2] = str.length() * 8;

        return strByte;
    }

    /**
     * 调用函数
     * @param source 原始字符串
     * @return
     */
    public String getMD5(String source) {
        // 初始化
        init();
        int[] strByte = add(source);
        for (int i = 0; i < strByte.length / 16; i += 16) {
            int[] num = new int[16];
            for (int j = 0; j < 16; j++) {
                num[j] = strByte[i * 16 + j];
            }
            mainLoop(num);
        }
        return changeHex(Atemp) + changeHex(Btemp) + changeHex(Ctemp) + changeHex(Dtemp);
    }

    /**
     * 整数变成16进制字符串
     * @param a 整数
     * @return
     */
    private String changeHex(int a) {
        String str="";
        String tmp = "";
        for(int i=0;i<4;i++) {
            tmp = Integer.toHexString(((a >> i * 8) % (1 << 8)) & 0xff);
            if (tmp.length() < 2) {
                tmp = "0" + tmp;
            }
            str += tmp;
        }
        return str;
    }

    public static String md5(String source) {
        StringBuffer sb = new StringBuffer(32);
        try {
            MessageDigest md    = MessageDigest.getInstance("MD5");
            byte[] array        = md.digest(source.getBytes("utf-8"));
            for (int i = 0; i < array.length; i++) {
                sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).toUpperCase().substring(1, 3));
            }
        } catch (Exception e) {
            //logger.error("Can not encode the string '" + source + "' to MD5!", e);
            return null;
        }
        return sb.toString();
    }

    public static void main(String[] args) {
    	 String str = MD5Util.getInstance().getMD5("888888");
         String str1 = MD5Util.getInstance().getMD5("807990064@Qq");
         System.out.println(str);
         System.out.println(str1);
         System.out.println(md5(md5("..aa@H!Fu")+"45vadr8ongnopcl6"));

	}

}
